nano-svg

A fast SVG parser for Haskell. Bytes in, a flat array of shapes out.

For geometry renderers, rasterizers and UI toolkits that need SVG icons and static vector artwork as paths. The library parses and normalizes geometry; the caller handles rendering and viewport mapping.

Quick start

parseSvg :: ByteString -> Either String Document reads UTF-8 SVG directly from a strict ByteString—no text-decoding step needed.

import Graphics.NanoSvg
import qualified Data.ByteString as BS

main :: IO ()
main = do
  bytes <- BS.readFile "clock.svg"
  case parseSvg bytes of
    Left err -> putStrLn err
    Right doc -> print (documentSize doc, length (documentShapes doc))

A Document contains the viewport size, the viewBox and a SmallArray of Shapes in paint order. Each shape carries its path, the Matrix that maps it into the viewBox, and its resolved Style. Relative path commands, shorthands and basic shapes become a common set of absolute path segments. The renderer walks segments without resolving an SVG tree, style inheritance or a transform stack. It still tracks the current point and subpath start.

encodeSvg :: Document -> ByteString writes a document back out as SVG, one path per shape; svgBuilder gives the same as a bytestring Builder. Parsing the result gives back the same shapes.

SVG scope

Supports paths, rectangles, circles, ellipses, lines, polylines and polygons; groups and use references; fills, strokes and inline styles; and SVG transforms. The focus is the static geometry used in icons and vector assets.

Not supported: gradients, patterns and other paint servers; text; clipPath, mask and filter; marker; CSS in a style element or an external sheet, and so class selectors; animation; and preserveAspectRatio, which is left to the renderer.

Unknown elements are skipped along with their children. Group opacity is multiplied into each shape rather than preserved as a compositing group. Nested svg and referenced symbol elements do not establish viewports.

Modules

Build

cabal build
cabal test
cabal haddock --open